Add window icons to ImGui viewports

[junnys6018]

Version/Branch of Dear ImGui:

Version: v1.72b
Branch: docking

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_glfw.cpp + imgui_impl_opengl3.cpp
Compiler: MSVC
Operating System: Windows 10

Is it possible to add window icons to Imgui viewports?
I am currently running the following code inside ImGui_ImplGlfw_CreateWindow()
to add icons. But it would be nice if an api was provided to set a default icon

static void ImGui_ImplGlfw_CreateWindow(ImGuiViewport* viewport)
{
...
int width, height, nrChannels;
unsigned char* img = stbi_load("res/icon.png", &width, &height, &nrChannels, 4);
GLFWimage icon = { width,height,img };
glfwSetWindowIcon(data->Window, 1, &icon);
stbi_image_free(img);
...
}

Screenshots/Video

[ocornut]

I am not sure it is easy or possible to provide a cross platform API for that without dragging in a lots of things. I think we should let the user implement it themselves in particular because I would expect some application may even want to have different icon depending on the content of the viewport.

For now my suggestion is to avoid modifying ImGui_ImplGlfw_CreateWindow():

Instead you can replace the Platform_CreateWindow or Platform_ShowWindow field of ImGuiPlatformIO. Save the previous handler, register yours instead. In your handler call the previous handler and then do your icon loading (if you do it in Platform_CreateWindow do it after calling the original handler, if you do it in Platform_ShowWindow do it first).

Open to other suggestions but I think this would be the path of least resistance and more flexibility for now.